Make chat input an auto-growing textarea

Replace the single-line input with a textarea that starts at one line,
grows vertically as text wraps (up to 7 lines), then scrolls. Override
daisyUI's .textarea min-height:5rem so the resting state is one line.
Enter sends, Shift+Enter inserts a newline.

1 files changed, 34 insertions, 8 deletions

diff --git a/packages/frontend/src/lib/components/ChatInput.svelte b/packages/frontend/src/lib/components/ChatInput.svelte
index 098856a..0c99078 100644
--- a/packages/frontend/src/lib/components/ChatInput.svelte
+++ b/packages/frontend/src/lib/components/ChatInput.svelte
@@ -1,7 +1,9 @@
 <script lang="ts">
 import { tabStore } from "../tabs.svelte.js";
 
-let inputEl: HTMLInputElement | undefined;
+const MAX_LINES = 7;
+
+let inputEl: HTMLTextAreaElement | undefined;
 let inputValue = $state("");
 
 const agentStatus = $derived(tabStore.activeTab?.agentStatus ?? "idle");
@@ -11,6 +13,29 @@ $effect(() => {
 	inputEl?.focus();
 });
 
+function resize() {
+	const el = inputEl;
+	if (!el) return;
+	// Reset height so scrollHeight reflects the content's natural height.
+	el.style.height = "auto";
+	const style = getComputedStyle(el);
+	const lineHeight = Number.parseFloat(style.lineHeight) || 20;
+	const paddingY = Number.parseFloat(style.paddingTop) + Number.parseFloat(style.paddingBottom);
+	const borderY =
+		Number.parseFloat(style.borderTopWidth) + Number.parseFloat(style.borderBottomWidth);
+	const maxHeight = lineHeight * MAX_LINES + paddingY + borderY;
+	const next = Math.min(el.scrollHeight, maxHeight);
+	el.style.height = `${next}px`;
+	el.style.overflowY = el.scrollHeight > maxHeight ? "auto" : "hidden";
+}
+
+// Re-run resize whenever the value changes (covers programmatic clears too).
+$effect(() => {
+	// Touch inputValue so this effect tracks it.
+	void inputValue;
+	resize();
+});
+
 function handleKeydown(e: KeyboardEvent) {
 	if (e.key === "Enter" && !e.shiftKey) {
 		e.preventDefault();
@@ -26,7 +51,7 @@ function submit() {
 }
 </script>
 
-<div class="flex items-center gap-2 p-3">
+<div class="flex items-end gap-2 p-3">
 	{#if agentStatus === "running"}
 		<button
 			type="button"
@@ -38,24 +63,25 @@ function submit() {
 			<span class="text-xs">Stop</span>
 		</button>
 	{:else if agentStatus === "idle"}
-		<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round" class="w-5 h-5 text-success">
+		<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round" class="w-5 h-5 text-success shrink-0 mb-2">
 			<polyline points="20 6 9 17 4 12"></polyline>
 		</svg>
 	{:else if agentStatus === "error"}
-		<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="w-5 h-5 text-error">
+		<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="w-5 h-5 text-error shrink-0 mb-2">
 			<circle cx="12" cy="12" r="10"></circle>
 			<line x1="12" y1="8" x2="12" y2="12"></line>
 			<line x1="12" y1="16" x2="12.01" y2="16"></line>
 		</svg>
 	{/if}
-	<input
+	<textarea
 		bind:this={inputEl}
 		bind:value={inputValue}
-		type="text"
+		rows="1"
 		placeholder="Type a message..."
-		class="input input-ghost flex-1"
+		class="textarea textarea-ghost flex-1 resize-none leading-normal !min-h-0 h-auto"
 		onkeydown={handleKeydown}
-	/>
+		oninput={resize}
+	></textarea>
 	<button
 		type="button"
 		class="btn btn-primary"